I went for a 10-15 mile demo ride on a Spyder a while back. Very interesting machine to try. It really does handle a lot like a quad on the street, just like someone else said. If you're used to riding bikes and have no quad or snowmobile experience, the first time you turn a corner, you'll feel like the Spyder wants to throw you off. A Spyder might actually take more strength to ride than a bike, except for at low speeds.
Overall I'd say the Spyder is really not for me for a few reasons:
-I like to lean the right way around corners, not the wrong way.
-It's very slow compared to a "real" motorcycle. I suppose it can run with most cruisers, but that's not saying much.
-The stability control system is very intrusive. If you get too frisky in tight corners, it quite abruptly cuts fuel/spark and the bike virtually shuts down for a second. You can forget about sliding/spinning the rear wheel if the bike is even fractionally turning or going sideways.
-I think Bombardier missed the mark on the engine. They obviously wanted to stay in the company and use a Rotax engine that was already EPA'd due to its use in Aprilia motorcycles. But while it's a decent bike engine (I own a Tuono), it's just lacking in power or smoothnes pushing something as heavy as the Spyder. A 1.5 liter four or triple might have been a better choice. It's not like the current motor is especially good on gas...how much worse would a bigger engine be?
It's not my cup of tea, but I will say that I'd much rather ride and own a Spyder than ANY bike converted into a trike. Those things are just abortions. I respect my elders and all, but come on, get a convertible if you can no longer hold up your Wing or Electra Glide. At least a Spyder has a modicum of engineering behind it and can build up to some pretty impressive cornering speeds.